------->php code optimization and PHP related problems summary

Problem | Optimization 1, in a function, when passing an array
Using return is more efficient than using global
Like what


function Userloginfo ($usertemp) {
$detail =explode ("|", $usertemp);
return $detail;
}
$login =userloginfo ($USERDB);

Than

function Userloginfo ($usertemp) {
Global $detail;
$detail =explode ("|", $usertemp);
}
Userloginfo ($USERDB);



To be efficient

2, (this code is used to get the program directory corresponding URL, recommended use)

$urlarray =explode ('/', $HTTP _server_vars[' Request_uri '));
$urlcount =count ($urlarray); unset ($urlarray [$urlcount-1]);
$ofstarurl = ' http://'. $HTTP _server_vars[' http_host '].implode ('/', $urlarray);

This piece of code is better than

$pre _urlarray=explode ('/', $HTTP _server_vars[' http_referer '));
$pre _url=array_pop ($pre _urlarray);

To be efficient

3, in the cycle of judgment, the value of the use of identity is equal to the efficient
$a =2; $b = 2;
Like what
if ($a = = $b) $c = $a;
Than
if ($a = = = $b) $c = $a;
Efficient

Use where in less limit when 4,mysql queries
Limit check more than a few records, the speed is very fast, but the most of the query will be slow
Use in. On query continuity record, very fast, discontinuous records first run will be slightly slower, but later will be faster!

5,NT Server data operations are less stable than unix/linux

6, use Ob_start () as far as possible before using the output; Can speed up output speed, suitable for NT or Nuli/linux, Unlix Class Server if Use Ob_start (' Ob_gzhandler '), output efficiency will be higher

7, as far as possible use if ($a = = his value) to use if (empty ($a) when the negation, because the program runs faster

8, the use of unequal!= and <> efficiency is equivalent

9, personal experience to use $a = "11111111111111"; The efficiency and $a = ' 11111111111111 '; Quite. Not as much as the book says.

10, the use of standardized SQL statements, will be conducive to the analysis of MySQL

11, using

if ($online) {
$online 1= $online;
Setcookie (' Online1 ', $online, $cookietime, $ckpath, $ckdomain, $secure);
}



The cookie will take effect immediately.
Use

if ($online)
Setcookie (' Online1 ', $online, $cookietime, $ckpath, $ckdomain, $secure);



Cookies need to be refreshed again to take effect

12, using

$handle =fopen ($filename, WB);
Flock ($handle, lock_sh);
$filedata =fread ($handle, FileSize ($filename));
Fclose ($handle);

Than

File ($filename);

Be good at speed and stability.

13, truncate the string optimization function (to avoid the occurrence of a character)

function Substrs ($content, $length) {
if (strlen ($content) > $length) {
$num = 0;
For ($i =0 $i < $length-3; $i + +) {
if (Ord ($content [$i]) >127) $num + +;
}
$num%2==1? $content =substr ($content, 0, $length-4): $content =substr ($content, 0, $length-3);
$content. = ' ... ';
}
return $content;
}



such as $newarray[1]=substrs ($newarray [1],25);

14, the program in the case of shielding

For ($asc =65 $asc <=90; $ASC + +)
{//strtolower () This function will generate garbled characters on some servers!
if (Strrpos ($regname, Chr ($ASC))!==false)
{
$error = "In order to avoid user name confusion, the user name is forbidden to use uppercase letters, please use the lowercase letter";
$reg _check=0;
}
}




15, do not use file (), and do not use Fget ();(instability or slow) to take an array of functions

function OpenFile ($filename, $method = "RB")
{
$handle = @fopen ($filename, $method);
@flock ($handle, lock_sh);
@ $filedata =fread ($handle, FileSize ($filename));
@fclose ($handle);
$filedata =str_replace ("\ n", "\n<ofstar:>", $filedata);
$filedb =explode ("<ofstar:>", $filedata);
Array_pop ($filedb);
$count =count ($filedb);
if ($filedb [$count -1]== ') {unset ($filedb [$count-1]);}
return $filedb;
}
This function, although the code is more, but in the speed and stability of a great advantage!